Evaluation of the argument a. Phase One: Are the premises innocuous? That is, can they be accepted by one not antecedently committed to the Theory of Forms? (Remember, Plato is arguing for the existence of Forms from features of the concept of knowledge.) To claim that knowledge is infallible seems innocent enough, for all it seems to say is that knowledge entails truth: Necessarily, if you know that q , then q is true. But Plato slides from this innocuous reading of the premise to a more controversial one: that the things that we know are necessary truths ; that what we know is not merely an existent, but something which must exist (a necessary being ). In the case of ‘is e ’, the transition is from “What is known must exist” to “What is known is a necessary existent.” In the case of ‘is v ’, the transition is from “What is known must be true” to “What is known is a necessary truth.” But this is a now-familiar modal fallacy, conflating the necessity of a conditional

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Unformatted text preview: statement ( necessitas consequentiae ) with the necessity of the consequent of that statement ( necessitas consequentis ). Necessitas consequentiae Necessitas consequentis necessarily (if p , then q ) vs. if p then necessarily q ( p q ) vs. p q ( p q ) may be true even though both p and q are contingent truths. Hence, it does not entail p q . Example: Necessarily, if Toms shirt is crimson, then Toms shirt is red. (Being crimson entails being red.) But although Toms shirt is crimson, it is not a necessary truth that Toms shirt is red. The color of Toms shirt is a contingent matter. Cf. Parmenides treatment of the claim what exists must exist. This fallacy vitiates phase one of Platos argument: the argument that takes us from the truism that knowledge entails truth to the controversial thesis that what is known is a necessary truth....
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